Former long time Unitarian and now long time Trinitarian Andrew Schumacher has set up on his blog "The Trinity Series" where he presents an introductory case for and defense of the doctrine of the Trinity. His materials are especially informative and useful because he understands the mind and rationale of Unitarians because he himself was a Unitarian for many years. So his evidences and arguments are ones that can specifically address Unitarian concerns and objections. I HIGHLY RECOMMEND the series.
